1. Field of the Invention
The present invention relates to a photo-detection adapter for an automatic flash device wherein a flash light amount is controlled in accordance with a reflected light from a photographic object.
2. Prior Arts
A reflector lamp or a strobe has been used as an artificial light source for general photographing, as well as for a close-up photographing. When the close-up photographing is carried out by using a reflector lamp, there arises a problem due to radiation heat from the lamp. In particular, such radiation heat can not be ignored for photographic objects which are sensitive to the heat or are living things.
On the other hand, for the close-up photographing ring flash lamps are known, which are disposed circularly around the photographic lens. But, hitherto such ring flash lamp devices have no automatic control means, by which a radiation light amount is automatically controlled. Therefore, it is necessary to calculate an exposure value when they are used instead of a strobe. The exposure value is liable to be affected largely by a slight photographic distance variation for the close-up photographing, and accordingly it becomes extremely troublesome to obtain a suitable exposure value.
When a usual automatic control strobe is used for the close-up photographing, it is not necessary to calculate the abovementioned exposure value. But there are some other problems. Since a photo-detecting means for receiving a reflection light from a photographic object is normally disposed on the front face of the main body of the strobe, it does not receive a sufficient amount of the reflection light from the photographic object closely facing to the camera, and therefore a correct automatic control operation can not be expected.
In some automatic control strobes, it is possible to mount the photo-detecting means at an appropriate place outside the main body of the strobe by using a connection cord. However, in such a case the photo-detecting means is attached to a mounting shoe of the camera or a bracket for fixing the strobe to the camera body in order to enable the photographer to make a bounce photographing. The photo-detecting means is still far from the photographic object, and therefore it is also impossible to sufficiently receive the reflection light from the photographic object close to the camera in the closeup photographing.